Teach him to walk behind.You can start in the house with him tethered too you and tell him behind.if you have a fence in your yard walk close to the fence so he can't pass you on you left.if he tries to pass on the right get him on the left side again.

With the pulling.when he starts to pull stop and give a pop of the leash to the side.tell him steady and when the leash is slack with a dip in it start walking again.if he comes to you that is even better.

If your going to use a head halter i would use a halti as it sits better the the GL.also the Newtrix head halter is an awesome choice and works great for stopping pulling.

With the walking behind you can also have a treat in your hand keeping him behind telling him good boy good behind.